(Instance name (nickname) Lowest level you can get in (recommended levels))
Ragefire Chasm (RFC) 8 (13-20)Wailing Caverns (WC) 10 (17-23)
The Deadmines (DM or VC) 10 (17-23)
Shadowfang Keep (SFK) 10 (18-23)
Blackfathom Deeps (BFD) 10 (22-27)
Stormwind Stockade (Stocks or Stockade) 15 (23-27
Razorfen Kraul (RFK) 15 (22-31)
Gnomeregan (Gnomer) 15 (25-32)
The Scarlet Monastery: Graveyard (SM GY) 20 (29-35)
The Scarlet Monastery: Library (SM Lib) 20 (31-35)
Razorfen Downs (RFD) 25 (33-37)
The Scarlet Monastery: Armory (SM Arm) 20 (33-37)
The Scarlet Monastery: Cathedral (SM Cath) 20 (35-45)
Uldaman (Ulda) 30 (35-45)
Zul'Farrak (ZF) 35 (42-46)
Maraudon (Mara) 30 (39-49)
Temple of Atal'Hakkar (Sunken Temple, ST) 35 (47-52)
Blackrock Depths (BRD) 40 (48-60)
Dire Maul: East (DM East) 45 (55-60)
Lower Blackrock Spire (LBRS) 45 (54-60)
Dire Maul: West (DM West) 45 (57-60)
Dire Maul: North (DM North) 45 (57-60)
Stratholme (Strat) 45 (56-60)
Scholomance (Scholo) 45 (56-60)
(Note: All Outlands instances below have heroic versions of the instance available at level 70)
Hellfire Citadel: Hellfire Ramparts (Ramps) 55 (60-62)
Hellfire Citadel: The Blood Furnace (BF) 55 (61-63)
Coilfang Reservoir: Slave Pens (SP) 55 (62-64)
Coilfang Reservoir: The Underbog (UB) 55 (63-65)
Auchindoun: Mana-Tombs (MT) 55 (64-66)
Auchindoun: Auchenai Crypts (AC) 55 (65-67)
Caverns of Time: Escape from Durnholde Keep (OH, DH, DK or Durn) 66 (66-68)
Auchindoun: Sethekk Halls (AS, Seth, Seth Halls) 55 (67-69)
Coilfang Reservoir: The Steamvault (SV) 55 (68-70)
Auchindoun: Shadow Labyrinth (SL or Slabs) 65 (69-70)
Hellfire Citadel: Shattered Halls (SH or Shatt Halls) 55 (69-70)
Caverns of Time: Opening the Dark Portal aka Black Morass (BM) 66 (70)
Tempest Keep: The Mechanar (Mech) 67 (70)
Tempest Keep: The Botanica (Bot) 67 (70)
Tempest Keep: The Arcatraz (Arc) 65 (70)
Magisters' Terrace (MgT, Terrace) 65 (70)
(Note: All Northrend instances below have heroic versions of the instance available at level 80)
Utgarde Keep (UK/UTK) 65 (70-72)
The Nexus (Nexus/Nex) 66 (71-73)
Azjol-Nerub (AZN/AN) 67 (72-74)
Ahn'kahet: The Old Kingdom (ANK/OLD/AKO/OK) 68 (73-75)
Drak'Tharon Keep (DTK) 69 (74-76)
The Violet Hold (VH) 70 (75-77)
Gundrak (GD) 71 (76-78)
Halls of Stone (HOS) 72 (77-79)
Halls of Lightning (HOL) 75 (80)
The Oculus (Occ) 75 (80)
Caverns of Time: Culling of Stratholme (Culling/COS) 75 (80)
Utgarde Pinnacle (UP) 75 (80)
Trial of the Champion (Champ/ToC) 75 (80+)
(Note: All Cataclysm Instances below will have heroic versions of the instance available at level 85)
Throne of the Tides (ToT) 80-81
Blackrock Caverns (BC) 80-81
The Stonecore (SC) 82-84
Vortex Pinnacle (VP) 82-84
Lost City of Tol'vir (LCoT) 85
Grim Batol (GBD) 85
Halls of Origination (HoO) 85
Raids:
Upper Blackrock Spire (UBRS) 45 (56-60)
Zul'Gurub (ZG) 50 (56-60+)
Molten Core (MC) 50 (60+)
Blackwing Lair (BWL) 55 (60+)
Ruins of Ahn'Qiraj (RAQ or AQ10) 50 (60+)
Temple of Ahn'Qiraj (TAQ or AQ40) 50 (60+)
(Burning Crusades Raids)
Karazhan (Kara) 68 (70+)
Gruul's Lair (Gruul) 65 (70+)
Hellfire Citadel: Magtheridon's Lair 65 (70+)
Zul'Aman (ZA) 70 (70+)
Coilfang Reservoir: Serpentshrine Cavern (SSC) 70 (70+)
Tempest Keep: The Eye (TK) 70 (70+)
Caverns of Time: Battle for Mount Hyjal (Hyjal) 70 (70+)
Black Temple (BT) 70 (70+)
Sunwell Plateau (Sunwell) 70 (70+)
(Northrend Raids)
Naxxramas (Naxx10/Naxx25) 80 (80+)
Obsidian Sanctum (OS/Sarth10/25) 80 (80+)
Vault of Archavon - Archavon (Vault/VoA10/25) 80 (80+)
The Eye of Eternity (Maly/EoE10/25) 80 (80+)
Vault of Archavon - Emalon (Vault/VoA10/25) 80 (80+)
Ulduar (Uld10/25) 80 (80+)
Vault of Archavon - Koralon (Vault/VoA10/25) 80 (80+)
Trial of the Crusader (TC/TotC10/25) 80 (80+)
Onyxia's Lair (Ony10/Ony25) 80 (80+)
Trial of the Grand Crusader (TGC/ToGC10/25) 80 (80+)
Vault of Archavon - Toravon (Vault/VoA10/25) 80 (80+)
Ruby Sanctum (RS/Hal10/25) 80 (80+)
Icecrown Citadel (ICC) 80 (80+)
(Cataclysm Raids)
Bastion of Twilight (BoT) 85 (85+)
Throne of the Four Winds (TFW) 85 (85+)
Blackwing Descent (BD) 85 (85+)
